The neglected diversity of the Ochthebius fauna from Eastern Atlantic and Central and Western Mediterranean coastal rockpools (Coleoptera, Hydraenidae)

Abstract

We describe four species of Ochthebius subgenus Cobalius (Coleoptera, Hydraenidae) from coastal rockpools of the western Palaearctic Region: O. anzar sp. nov. (south Morocco, plus a possible specimen from Lanzarote, Canary Islands), O. cortomaltese sp. nov. (Malta), O. evae sp. nov. (Atlantic coast of Morocco and Mediterranean coast of south Spain), and O. gorgadensis sp. nov. (Ilha de Santiago, Cabo Verde). A molecular phylogeny of all described species of Cobalius recovered three clades: (1) O. serratus Rosenhauer, 1864 as sister to the newly defined O. algicola group, including most of the Macaronesian species of Cobalius (O. algicola Wollaston, 1871 from Madeira, O. freyi d’Orchymont, 1941 from Azores, O. lanthanus Ribera and Foster 2018 from Gran Canaria and Lanzarote, and O. balfourbrownei Jäch, 1989 and O. gorgadensis sp. nov. from Cabo Verde); (2) O. anzar sp. nov. as sister to the species of the newly defined O. biltoni group (O. biltoni Jäch and Delgado, 2017 from Sicily, plus O. evae sp. nov. and O. cortomaltese sp. nov.); and (3) the newly defined O. lejolisii group, including O. lejolisii Mulsant and Rey, 1861 (Atlantic coast from south Morocco to the British Islands) plus O. subinteger Mulsant and Rey, 1861 (western Mediterranean), O. adriaticus Reitter, 1886 and its subspecies, O. celatus Jäch, 1989 and O. asper Sahlberg, 1900 stat. rev., previously considered a synonym of O. subinteger (all from the Central and Eastern Mediterranean). We note the strong intrapopulational morphological variation and the contrasting lack of consistent diagnostic characters between populations, despite the deep genetic divergence between lineages found within some species. We also discuss the widespread evolutionary convergence in beetles living in coastal habitats, sometimes in different genera or even families.